Development and validation of molecular markers for grain cadmium in durum wheat

Durum wheat is capable of accumulating cadmium, a toxic heavy metal, in the grain at levels that have been deemed unsafe for human consumption. Previous studies have identified genetic variation as well as markers associated with Cd accumulation in durum wheat, which can be exploited to develop low Cd cultivars. Because the phenotyping for Cd content is very expensive, KASP markers were developed from molecular markers associated with grain Cd and tested for their usefulness for marker-assisted breeding. A total of 1278 unique genotypes from preliminary and advanced yield trials grown at multiple locations for 2 years were evaluated for grain Cd as well as screened for markers associated with Cd uptake. One marker on chromosome 5B was polymorphic in all crosses between high and low Cd parents and had r2 values ranging from 0.38 to 0.85. Two other markers on the same chromosome predicted similar levels of variation in many trials; however, they were not polymorphic in all populations. The KASP markers accurately predicted up to 97% of the lines for Cd phenotype in different trials. This study identified two markers, Cad-5B and Ex_c1343_2570756, with an average prediction accuracy of 84–88%. These markers could be useful for marker-assisted selection for low grain Cd in durum wheat.